US1999984A

US1999984A - Steam boiler

Info

Publication number: US1999984A
Application number: US701426A
Authority: US
Inventors: Ervin G Bailey; Perry R Cassidy; Ralph M Hardgrove; David S Jacobus
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1933-12-08
Filing date: 1933-12-08
Publication date: 1935-04-30
Anticipated expiration: 1952-04-30

Description

'7 Sheets-Sheet 1 Aprilj 30, 1935. E fG. BAILEY Er AL STEAM BOILER' l l Filed Dec. a, 1953 April 30r1935 E. @BAILEY Er AL 1,999,984

STEAM BoILg I Filed Deo. s, `193s 7 sheets-sheet 2 Fig?? 1- f 11 oo oo oo o oo o oo oo oo oo oo oo oo oo oo oo oo oo oo po oo oo oo oo oo oo oo oo oo oo OO OQ OO 00 00006 OOO 00000 Q00 00000 O00 00000 OOO OOOO INVENTORS Ervzn G. Bazlqy Perry E. Cassm'y BY Pal/gh M Hardgrove Ddl/Id 5. Jacobus TToRNEY April 30, 1935.

E. G. BAILEY ET Al.

STEAM BOILER fFiled Dec. a, 1953 '7 Sheets-Sheet 3 INVENTORS VJOS v wru www@ n mama M @P Ms. m .mUMm A NJW Ewpp l @mi April 30, 1935. E. G. BAILEY Er Al. 1,999,984l STEM BoILER l vFiled Dec. e, 195s 7 sheets-sheet 4 asa-1 'g M. Ha y Us ATTORNEY INVENT RS Ervin (oail Perf' E. G. BAILEY ET AL STEAM BOILER- Filed Dec. 8, 1933' Aprl 3o, 1935.-

7 Sheets-Sheet 5 INVENTORS. AErl/111 G. Halley l Perry E. Cassidy BY Ralph /1/1. Hardy/'ove Davia' S. Jacabus E. G. BAILEY E-r Al.

STEAM BOILER April 30, 1935. 1,999,984

Filed Dec. s, 19:53 "7 sheets-sheet 6 INYENTORS n Erl/1n G. Baz/ey Perry l?. Cassidy BY Ralph M Hrdgrove ,David S Jacobus Patented Apr, 30, 1935 vUNITED sTATEs `PMI-:livr oFFicE 'incassi STEAM riforma pany, Newark, N. J. Jersey a corporation of New Application December s, 193s, sel-iai No. '101,426

v. 29 Claims.

pacity are particularly applicable to industrial vision of a steam boiler of the character de-` plants and marine installations.l

-The general object of our invention is the proscribed which is further characterized by a substantial reduction'in the head-room requirements, a relatively low cost of construction, and a capacity for operation at high ratings with a low draft loss, good efficiency and high superheat temperatures. A further object is the provision of a furnace construction and arrangement in a steam boiler of thecharacter described which is adapted for the burning of fuel at high efficiencies, and particularly of a fluid fuel, such as pulverized coal, oil or gas, in suspension. A further object is the provision of a two drum steam boiler of the character described having a highly compact and thermally effective arrangement of the fluid heating surface thereof relative to the boiler furnace and the flow of heating gasesfrom the furnace. A still further object is the provision of a two drum steam boiler construction which is adapted for' standardization in" a series of sizes or classes of different horse power capacities with little or no variation in -the draft loss and exit gas temperature throughout the series. A .further Object is an improved superheater construction and arrangement in a boiler of the character described in which slagging of the superheater tubes is minimized, high steam temperatures obtained with a minimum of superheater surface, superheater tube temperatures maintained within safe limits, and a relatively 'fiat superheat curve attained. A further specific object is the provision of a low cost uid cooled furnace shaped to provide an effective utilization of its volume for burning the fuel, and constructed to simplify the boiler supporting structure,

facilitate the removal of the fuel residue, whether y a part ofI this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use,

.have illustrated and described preferred ments of our invention.

Of the drawings:

Fig. 1 is a sectional elevation taken on the line l-I of Fig. 2 and illustrating one embodiment of our invention; Fig. 2 is a plan' section taken on the line 2--2 of Fig. 1; Figs. 3 and 4 are enlarged views of the tube bank bailles shown inFig. 2; Fig. 5 is a vertical section taken on the line 5-5 of Fig. 2; Fig. 6 is a vertical sectiontaken on the line 6-5 of Fig. 5; Fig. 6A is an enlarged view of a portion of the furnace floor; Figs. 7 and 8 are elevation and bottom views respectively of the header connection; Fig. 9 is an enlarged detail of the partition taken on the line 9-9 of Fig. 1; Fig. 10 is a vertical section taken on the line VI (1 -i0 of Fig. 9; Fig. l1 is a vertical section taken on the line lI--II of Fig. 2; Fig. 12 is a vertical section taken on the line l2-I2 of Fig. 2; Fig. 13A is a vertical section taken on the line I3--l3 of Fig. 12; Fig. 14 is a sectional elevation of a modified boiler construction taken on the line i 1 -ifi of Fig. 16; Fig. 15 is a vertical section taken on the line I5-I5 of Fig. 14;r and Fig. 16 is a plan section taken on the line Iii-i6 of Fig. 14.

embodi- In the steam boiler embodying our invention illustrated in Figs. 1 to 13 ofthe drawings, 2i! designates an upper horizontally arranged longitudinally extending steam and water drum having a submerged feed water Supply connection and steam outlets 22 adjacent one end. The drum 29 is connected to a similarly arranged lower water drum 23 by a vertically inclined bank of bent tubes 2t .extending between and connected to the -drums substantially throughout the length thereof. The drum 23 is supported on longitudinally spaced cradles 25 and anchored at its front end for relatively free longitudinal expansion and contraction rearwardly. The

drums

29 and 23 and tube bank 2li constitute the main steam generating section of the boiler, the weight of these parts being almost wholly supported by the cradles 25. The

drums

29 and 23 and tube bank 2li are positioned in a housing having vertical refractory front and rear walls 26 and 2lrespectively, and a side wall 28 at the youter side of the tube bank relative to the furnace. The opposite side wall 29 is laterally spaced a substantial distance from the inner side of the tube bank and constructed as hereinafter described. 'Ihe

walls

28, 2l, 28 and 29 thus form a boiler housing substantiallyrectangular in horizontal-cross section, as shown in'Fig. 2.'

The space between the inner side of the tube bank 24 and the

walls

26, 21 and 29 is utilized for the boiler furnace or combustion chamber 30 and is arranged to communicate at its rear end with the rear end of the spa/ce 2| occupied by the tube bank 24. The inner side wall 33 of the furnace chamber terminates short of the rear wall 21, and is advantageously 'formed by a partition comprising a rowof longitudinally spaced vertical tubes 24*l having their upper and lower ends connected to the drums and 23 respectively, and forming the innermost row of the tube bank 24. The tubes 24e are preferably of larger diameter than the tubes 24 in the remaining rows' and spaced from the adjacent row a greater distance transversely of the tube bank than the transverse spacing between the remaining rows in the tube bank. The tubes 24, as shown in detail in Figs. 9 and 10, have vertical rows of staggered'metallic studs 3| extending along opposite sides thereof and projecting into the intertube spaces. To prevent spreading of the tubes 24a the studs 3| on adjacent tubes are advantageously tied. together at points spaced along the tubes. At each of these points the studs on 'adjacent tubes are welded by jump welds to a vertical plate 3 2 positioned between the stud rows. The use of the plates 32 facilitates the manufacture 'and` assembly of the stud tubes. The intertube spaces containing the studs 3| are closed by suitable refractory material 33a applied in an initially plastic state and allowed to,set. The partition or wall 33 so formed extends only a portion of the length of the tube bank, leaving a space between its rear end and the rear wall 21 through which the furnace chamber and the tube space communicate. The tubes 24e receive heat on one side by radiation from the furnace chamber and on the opposite side by convection from the tube space.

The outer side wall 23 of the furnace chamber has its inner portion formed in substantially the same manner as lthe inner wall 33 `by a row of vertically arranged radiantly heated stud tubes 3.4 uniformly spaced throughoutthe length of the furnace chamber and refractory material 35 closing the intertube spaces and supported by the tube studs, as in Figs. 9 and 10. The tubes 34 have their lower ends connected to a substantially horizontal header 36 extending longitudinally of the furnace chamber slightly above the level of the axis of the mud drum 23 and supported on longitudinally spaced piers 33. The upper portions of the tubes 34 are similarly ,curved and inclined toward the tube bank 24 and connected into the drum 20 above the level of the tubes 24e and at or below the normalwater Y closed by heat resistant. blocks 4|, the at upper 10- level in the drum. 'I'he tubes 34 thus define the outer side wall and roof of the furnace chamber 30. One or more layers 31 of insulating material are arranged between the outer side of the tubes 34 and an outer metallic casing 38.

The floor of the furnace chamber is defined by a row of horizontally inclined radiantly heated water tubes 40 connecting the drum 23 to the header 36. The

tubes

40, 24e and 34 are substantially similarly spaced throughout most'of the length of the furnace chamber and the tubes 40 are covered and the spaces therebetween surfaces of which constitute a smooth :door extending from the front wall 2 6 to an ash pit 42 at the rear end of the furnace chamber. The blocks 4| are preferably secured to the tubes 46 by clamps 4| bridging adjacent tubes and c911- -nected to the blocks 4I, as shown in 6a. The

one or more fluid fuels, such as pulverized coal,

oil or gas, simultaneously or independently. The fuel burner is symmetrically arranged in the front wall 26 to discharge a stream of fuel horizontally through the furnace chamber toward its rear wall 21.

The stream of fuel directed. toward the rear 'wall of the furnace chamber might cause that wall to rapidly erode at high rates of operation or when a fuel having a low fusion ash is burned, and in the present construction the inner face of the rear wall is advantageously protected by a row-of transversely spaced vertical cooling tubes 50, arranged as shown in Figs. 1, 2 and 5. The tubes 50 have their lower ends connected to a horizontally inclined header 5| having its axis in horizontal alignment. with the axes of the floor tubes 40 and with the header end adjacent the drum 23 connected thereto` by a nipple 52. The upper portions of the tubes 56 are bent substantially parallel to the tubes 34 and connected in a circumferential row to the steam and water drum 20. The lower ends of certain rear wall tubes 50 are bent oppositely at opposite sides of clean-out openings 53 and inspection or lance openings 54. Similar openings are also made in the refractory front wall 26. 'The tubes 50and header 5I are slightly spaced from the rear wall to permit rearward movement thereof on expansion of the boiler drums and/or header 36.

In order to facilitate closing the corner of the furnace between the walls 21 and 29, an additional oor tube 40 is provided alongside the header 5|. The upper lsurfaces of the header 5| and tube 40a are protected by a layer of refractory 55. In operation, the floor tubes tend to expand axially and move the header 36 laterally. The tube 40 being widely spaced from the adjacent tube 40 would have little effect on the corresponding portion of the header 36. To prevent deformation of the tube 40"L on expansion thereof and to provide simultaneously movement of the headers 5| and 36 on elongation of the latter, a plate 56 is welded to the underside of the header 36 andprovided with an opening 51 in a portion thereof below the header 5| into which a lug 58 on the underside of the header 5| fits.

' The ash pit 42 in the furnace illustrated extends across the rear end of the furnace chamber in front of the rear wall 21, in which is formed a series of spaced clean-out openings 59`closed by doors 60. The ash pit has a refractoryiioor 6|, si'de walls 62, and a vertical front wall 63, which has a seal joint permitting relative longitudinal expansion of the furnace floor. The last pair of floor tubes 40 are connected by a spacer bar 4||b welded thereto, as shown in Fig. 6A. A

seal plate 4|| extends downwardly from the lower side of the last tube 40. The joints between the ash pit walls`62 and the header 36 and drum 23 are protected by a refractory layer, the rear portion of the header 36 being studdedas shown in Fig. 5, to hold the refractory inposition. The furnace floor may be cleaned by'tools inserted through the openings 58 and the fuel residue collected removed from the ash pit through the openings 58 at the boiler room floor level. The oor and ash pit construction may be changed or the ash pit omitted depending upon .the character of the fuel burned and the condition of the fuel residue deposited on the furnace oor. Where, for example, the fuel burning provisions are not intended for burning an ash-forming fuel, the ash pit may be omitted and the furnace fioor continued to the rear wail'21.

In prior two-drum boiler constructions of the general character described, it has been customary to cause the heating gases to flow horizontally through a single pass longitudinally of the convection heated tube bank. Such a construction is not practical for. the basis of a commercial line of boilers having different maximum steam generating capacities while maintaining substantially the same draft loss and exit gas temperature. The addition of steam) generating surface in such boilers results either in an undesirable change in the furnace shape, an undesirable decrease in the-drum ligament strength, or an in: crease in the draft loss. The single pass arrangement is further disadvantageous as it offers substantially no flexibility of control of the mass flow of heating gases over the tube bank. With the present construction, a series of boiler sizes with similar tube spacings may be obtained while maintaining substantially the same draft loss and without changing the furnace transverse cross-sectional area and shape, by merely changing the total number of transverse rows of tubes Iand correspondingly :changing the number of y 2, the tube bank space 2| is advantageously divided into a plurality ofv serially connected gas passes 18, 1I and 12, extending transversely of the tube bank and through which a substantially horizontal iow of heating gases is maintained from the furnace chamber to a gas outlet 13 in the front end of a at arch 14 extending between the drum 2@ and housing wall 28. Sloping baffles 15 and 16 separate the. gas passes 18, 1| and 12. As shown in Figs. 2, 3, 12 and 13, the baille 15 extends between the drums from the inner furnace chamber wall 33 toward the housing wall 28 terminating short of the latter to permit communication between the gas passes 1li and 1l. A pair of tubes 24b at the rear end of the chamber wall have studs 3 i on their outer sides which support a layer of refractory material 33h in which a notch 11 is formed to receive the inner end of the baffle 15. The baffle 15 is formed by superposed rows of tile, as shown in Fig. 12, which are held between thelast transverse row of tubes 24 and a transverse row of large diameter tubes 28C hereinafter described. The superposed tile 'iiia adjacent the furnace chamber wall 33 are provided with tongue and groove joints, as shown gaspass 1,0 are fewer in number but of' greater diameter than the tubes in the second and third passes 'H and 12. The tubes of the innermost rows in the nrst pass are bent and staggered, as shown in Figs. 2 and 11, to form a slag screen across the entrance end of the first pass. The remaining steam generating tubes 24 are arranged in longitudinal rows occupying only about one-half of the available space in the first pass. The tubes 24u serve as a water screen for a steam superheater positioned'in the first pass between the tubes 24c and the wall 28.

The steam superheater is formed by a series of nested single looped tubes 88 arranged substantially parallel to'the tubes 24 with their looped portions adjacent the drum 20 and their lower ends connected to a pair of longitudinally extending horizontal headers'ii I and 82 between the drum 23"and wall 28. The headers 8| and 82 are partitioned, as indicated in Fig. 2, to divide the superheater into passes for the serial flow of the steam therethrough. The header 82 receives the steam to be superheated at its forward end through the tubes 22 and has an outlet 82n formed on its rear endfor the discharge of the superheated steam. The superheater is supported entirely by the drum 23 through longitudinally,

spaced cantilever beams 83 in which the super- Aheater headers are. cradled. The superheater tube connections' and lower supports are pro- The horizontal load of the upper end of 24 through lugs 85 welded to the boiler tubes and opposite the superheater tubes, and transverse spacers 86a and longitudinal spacers 86 for holding the superheater tubes in spaced relation.

The amount of steam generating surface in the first pass is limited to that required to remove the slag from the furnace gases and to reduce the gas temperature to a value at which safe superheater tube temperatures result. With only this amount of steam generating surface contacting with the furnace gasesprior to their reaching the superheater, only a relatively small amount of superheater surface will be required to obtain a given steam superheat temperature and a less varying superheat curve will result. The use of large diameter tubes in the first pass is desirable with the high gas temperatures present. The use of small diameter superheater tubes in the rst pass and 'steamr generating tubes in the lsecond and third passes reduces the cost and space requirements and increases the boiler efficiency for a given amount of heating surface. The boiler and superheater tubes in the first pass can be easily'removed and replacedfrom the furnace chamber.

With the boiler construction described, feed water enters the drum 28 and flows downwardly throughsubstantially all of the tubes 24 in the gas passes 1I and 12. A considerable portion of the steam is generated in the furnace tubes 2li, 40 and 34 and the tubes 2lic in the first'pass. Fuel is preferably introduced through the front wall into the furnace chamber in a horizontal stream andis rapidly ignited `and burned'in suspension. The heating gases pass rearwardly through the furnace chamber and then transversely across the slag and water screen tubes 2lic Y in the gas pass 1l). The gases then contact with the superheater tubes 80 and turn around the baiie 15 into thegas pass 1 i After passing across the tubes 24 in the gas pass 1i, the gases turn through the space 81 between the innermost row of small diameter tubes 24 andthe inner furnace wall 33, the space 81 insuring proper distribution of the heating gases in the passes 1| and 12 and minimizing the amount of tube surface therein short-circuited. The heating gases tend to rise during their passage through the gas passes'and to prevent by-passing of the lower portions of the tubes in the third pass 12, spaced metal strip baffles 88 are mounted on the outermost tubes 24 in that pass, as shown in Fig. 1,' to cause most of the gases to turn downwardly below the bailied section before reaching the boiler gas outlet 13. Dampers 89 control the gas outlets 13. A brick wall 90 i's constructed at the front end of the refractory layer 84 to prevent the heating gases entering the space containing the superheater supports. The' uid heating surface in the furnace shown is preferably proportioned in amount and exposure to maintain a furnace temperature such that when a slag-,forming fuel is burned in suspension, a substantial portion of the particles of fuel residue deposited on the furnace floor will be cooled sumciently to permit their removal in a dry form.

The steam and water drum 20 contains suitable steam and water separating provisons for insuring the delivery of substantially dry steam to the superheater. The separator is preferably of the type disclosed and claimed in a pending application of James Fletcher, Serial No. 678,374, filed June 30, 1933. l

While the Whole vertical load of the drums and tube bank is carried by the supports for the mud drum, the vertically inclined arrangement of the tube bank and offsetting of the drums causes a horizontal load which is partly supported by the tubes 34 and the floor supports and partly by end horizontal beams 92 each having an inclined bracket 93 in contact with a similar bracket 84 on the drum, as shown in Fig. 1l.

In the modification illustrated in Figs.. 14 to 16 the upper and` lower drums |20 and |23 have their axes substantially in vertical alignment and the connecting tubes |24 upright. 'I'he inner wall of the `furnace |30 is formed by a refractory baille |33 supported between the innermost row of smallv diameter tubes |24 and a row of large diameter tubes |24". The innermost row of tubes |24 is laterally spaced from the remaining tube rows a substantial distance to provide a gas turning space |81 therebetween. The oor, outer side wall I 29, and roof of the furnace are defined by a row ci! longitudinally spaced continuous U-shaped tubes |34 having their oppositeends connectedto drums |20 and |23 respectively. 'I'he tubes |34 line the 'inner surfaces of the refractory forming the floor, outer side wall, and roof. The rear walldivided into serially connected transverse gas` passes |60, |6|, and |62 byrefractory baflles |64 and |65. 'I'he baille |64 forms a perpendicular extension of the rear end of the baille |33, while the baille |65 extends from the housing wall |28 towards, but terminating short of, the baille wall |33. The tubes |24a at the outer side of the baille |33 are uniformlyl spaced throughout the length of the furnace, extending across the entrance to the gas pass |60. The tubes |24 are similarly dis tributed and arranged in all of the gas passes, and those in the gas pass |60 provide a water screen for the superheater |80.- The superheater is formed by one or more large diameter looped tubes extending horizontally along the outer side of |22 of the drum |20, and provided with a drain connection |82 at its lowermost point to make the superheater self-draining.

With the above construction a stream of fluid fuel is projected horizontally toward the rear wall of the furnace, and the products of combustion pass rearwardly around the rear end of the baille wall |33 and successively through the heating gas passes |60, |6| and |62 to the heating gas outlet |63. The fluid ow in the boiler circulation system will be substantially the same as that described in the embodiment illustrated in Figs. l to 13, the ilow through the radiant heat absorbing furnace tubes and the steam generating tubes in the gas pass |60 being upward, while the flow through the tubes located in the passes |6| and |62 is generally downward. A considerable portion of the steam generated in the tube bank will be in the tubes located in the gas pass |60, and thesteam'outlet |22 from the drum |20 is located at the front end of the drum.

While in accordance with the provisions of the statutes we have illustrated and described herein the best forms of our invention now known to us, those skilled in the art will understand that changes may be made in the form of the boiler, furnace and fuel burning provisions disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes be used to advantage without a corresponding use of other features. s

We claim:

1. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, means forming a furnace chamber laterally adjoining the space containing said tube bank and communicating therewith at only one end, baille means extending transversely of said tube space and arranged to divide said tube space into a plurality of serially connected gas passes extending transversely 4of said tube bank, and means at the opposite end of said furnace chamber for burning fuel in said furnace chamber and effecting a substantially horizontal flow of heating gases longitudinally through said furnace chamber and reversely through said serially connected gas passes.

2. A steam boiler having van upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, means forming a fluid cooled furnace chamber laterally adjoining lthe space containing said tube bank and communicating therewith only at one end, means at the opposite end of said furnace chamber for burning fuel in suspension iny said furnace chamber and effecting a substantially horizontal flow of heating gases longitudinally through said furnace chamber and reversely through said tube space, and transversely extending baille means arranged to divide said tube space .into a plurality of serially connected gas passes extending transversely of said tube bank.

3. A steam boiler having a substantially rectangular housing, en upper steam and water drum, an offset lower water drum, avvertically inclined convection heated bank of closely spaced steam generating tubes extending between andl connected to said drumssubstantially throughout the length thereof, a baille wall separating a laterally adjoining furnace chamber from the space containing said tube bank and terminating at its rear end short of the rear wall of said housing to provide communication therebetween at their rear ends only. a row of water tubes connected to said drums and in thermal contact with said partition, lanother row of water tubes connected to said drums-and laterally spaced from said tube bank and extending along the outer side wall of said furnace chamber, meansiat the front end of said furnace chamber for burning fuel in suspension in said furnace chamber and effecting a substantially horizontal flow of heatying gases longitudinally through said furnace chamber and reversely through said tube space, transversely extending baffle means arranged to divide said tube space into a plurality of serially connected gas passes extending transversely of said tube bank, and'said partition and partition cooling tubes being spaced from the adjacent tube bank row of tubes a transverse distance greater than the transverse distance between the longitudinal tube rows in the gas passes laterally adjoining said partition.

4. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and'connected to said drums along the length thereof, a partition defining the inner side wall of a furnace chamber laterally adjoining the space containing said tube bank and communicating therewith at one end..

fuel burning means at the opposite end of said furnace chamber, means effecting a substantially horizontal flow of heating gases longitudinally through said furnace chamber and reversely through said tube space, transversely extending baffle means arranged to divide said tube space into a plurality of serially connected gas passes extendingjransversely of said tube bank, and

' the tubes of said tube bank in the gas pass opening to saidfurnace chamber being of larger diameter than the tubes in the subsequent gas passes.

5. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums alongthe length thereof, means forming a fluid cooled furnace Achamber laterally ad- .joining the space containing said tube bank and communicating therewith at one end, said means including a row of vertically disposed water tubes laterally spaced from said tube bank and having ,their upper ends connected to said steam and water drum, integral projections on said water tubes, refractory. material carried yby said tube projections and defining the outer sidewall of said furnace chamber, tubes connecting the lower ends of said side wall tubes to said lower drum,

, and means at the opposite end of said furnace chamber for burning fuel in suspension in said furnace chamber and effecting a substantially horizon-tal flow of heating-gases longitudinally through said kfurnace chamber and reversely through said tube space and in thermal contact with'the tubes therein.

6. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heatedbank of steam generating tubes extending between and connected to said drums along the length thereof, means formv ing a fluid cooled furnace chamber lateralllr adjoining the space containing said tube bank and communicating therewith at one end, said means including a row of vertically disposed water tubes l laterally spaced from said tube bank and-having their upper ends connected to'said steam and water drum, refractory materialv closing the spacesl of heating gases longitudinally through said furnace chamber and thence through said tube space and in thermal contact with the tubes therein.

7. A steam boiler-having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, means forming av fluid cooled furnace chamber laterally adjoining the space containing said tube bank and communicating therewith at one end, said means including a row of vertically disposed water tubes laterally'spaced from said tube bank andhaving their upper ends directly connected to said steam and water drum, refractory material closing the spaces between said water tubes and deflning the outer side wall and roof of said furnace chamber, a header connected tothe lower ends of said water tubes, a row of tubes connecting said header to said lower drum, refractory means closing the spaces between and covering said last named' tubes to define the iioor of said furnace chamber, a fluid cooled partition extending between said drums adjacent the`forward portion of said tube bank and defining the inner side wall of said furnace chamber,and means at the opposite end of said .furnace chamber for burning fuel in suspension in said combustion chamber and effecting a substantially horizontal flow of heating gases longitudinally through said furnace chamber and reversely through said tube space and in thermal contact with the tubes therein.

8. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes lextending between and connected to said drums along the length thereof, a partition deflning the inner side wall of a furnace chamber laterally adjoining the space containing said tube bank and communicating therewith at its rear end, means at the front end of said boiler for burning a slag-forming fuel in said furnace chamber and effecting a substantially horizontal flow of heating gases rearwardly through said furnace chamber and thence through said tube space and in thermal contact with the tubes therein, and means adjacent the rear end of said waterdrum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the defining the inner side wall of a furnace chamber laterally adjoining the space containing said tube bank and communicating therewith at one end, a row of water tubes connected to said drums and laterally spaced from said tube bank and extending along the outer side wall of said furnace chamber, a horizontal header connected to the lower ends of said side wall tubes, means at the opposite end of said furnace chamber for burning fuel in suspension in said furnace chamber and effecting a substantially horizontal ow of heating gases longitudinally through said furnace chamber' and reversely through said tube space, a horizontally extending header along the rear wall of said furnace chamber and connected to said lower water drum, a row of tubes connecting said rear wall'header and steam and water drum' and cooling the rear wall of said furnace chamber, and means forming a direct structural connection between said side and rear wall headers.

10, In 1a furnace, a wall comprising a row of spaced tubes, a multiplicity of metallic studs mounted on opposite sides of said tubes and projecting into the inter-tube spaces, refractory material carried by said studs and closing the inter-tube spaces, and means for tying adjacent tubes together at a point intermediate their length comprising means forming a welded con-- nection between studs on adjacent tubes.

.11. In a furnace, a wall comprising a row of spaced tubes, a multiplicity of metallic studs mounted on opposite sides of said tubes and projecting into the inter-tube spaces, refractory ma terial carried by said studs and closing the intertube spaces, and means for tying adjacent tubes together intermediate their length comprising a plate extending vertically between the studs on adjacent tubes and welds integrally connecting 4 said plate to studs on adjacent tubes.

12. In a tubular heat exchanger adapted as a part of a furnace wall to transmit to a contained fluid the heat received radiantly from fuel burni ing in the furnace; said tubular heat exchanger having a metallic inner part in contact with the contained uid; and a composite buter structure exposed to radiant heat from the burning fuel; said outer structure comprising metallic projections extending outwardly from the inner part, and refractory material contacting with the inner part Iand located between the projections, said refractory material being of greater,therma1 resistanc than themmaterial of the remaining structure, thereby preventing overheating of the exchanger metal and contributing to higher furnace temperatures, and means for integrally connecting the metallic projections on adjacent tubes.

13. A steam boiler having an upper steam and water drum; a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, a partition defining the inner side wall of a furnace chamber laterally adjoining the space containing said tube bank and communicatingA therewith at one end, means defining the remaining walls of said furnace 'chamber and tubeV space, means at the opposite end of said furnace chamber for burning fuel in said furnace chamber and effecting a substantially horizontal ow of heating gases longitudinally through said furnace chamber and reversely through said tube space and in thermal length thereof, a partition contact with the tubes ranged to divide said tube space into a plurality of serially connected gas passes extending transversely of said tube bank, and a .stear superheater positioned in the gas pass opening to' said furnace chamber.'

14. -A steam boiler having an upper steam and water drum. a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, a partition defining th'e inner side wall of a furnace chamber laterallyadjoining the space containing said tube bank and communicating therewith only at one end, means dening the remaining walls of said furnace chamber and tube space, means at the opposite end of said furnace 'chamber for burning fuel in said furnace chamber and effecting a substantially horizontal iiowbf heating gases longitudinally through said furnace chamber and reversely through said tube space and in thermal contact with' the tubes therein. baille means arranged to divide said tube space into a plurality of serially 'connected gas passes extending transversely of said tube bank, a steam superheater positioned in the gas pass opening to said furnace chamber, and water tubes in said last mentioned gas pass arranged to-form a screen between said superheater and ysaid furnace chamber.

l5. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and. connected to said drums along the length thereof, a partition taining said tube bank and communicating therewith only at one end, a row of spaced verticallydisposed water tubesl laterally spaced fromsaid tube bank and connected to said steam and water drum, refractory material closing the spaces between said water tubes and defining the outer side wall of said furnace chamber, a header connected to the lower end of said water tubes, a row of tubes connecting said header to said lower drum, means closing the spaces between said last named vtubes and defining the floor of said furnace chamber. means at the opposite end of said furnace chamber for burning fuel in suspension in said furnace chamber and effecting a vsubstantially horizontal flow of heating gases longitudinally through said furnace chamber and thence through said tube space and in thermal contact with the tubes therein, and an ash receiving opening extending transversely of said furnace chamber atthe rear of said floor tubes.

16; A steam boiler having an upper steam and water drum, a lower waterl drum, a vertically disposed convection heated bank o'f steam generating tubes extending between and connected to said drums alonglthe length thereof, va bottom support for said drums and tube bank, means forming a furnace chamber laterally adjoining the space containing said tube bank and communicating therewith at its rear end, means at the front end of said furnace chamber. for-buming fuel in said furnace chamber and effecting a substantially horizontal ow of heating gases rearwardly through' said furnace chamber and forwardly through said tube space, a superheater at the outer side of said tube bank having a pair of headers arranged parallel to said lower water drum 'and looped tubes connecting said headers arranged adjacent said tube bank, means for supporting said headers from said lower water therein, baille means'ardrum, and means forv laterally supporting said iboped tubes imm said tube bank.

17. Asteam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, means defining a furnace chamber laterally adjoining the space containing said tube bank and including a row of tubes having one end connected to said lower drum and extending laterally from said tube bank, a horizontal side -wall header connected to the other end of said laterally extending tubes, means for burning fuel in said furnace chamber, a header extending along an end wall of said furnace chamber substantially parallel to said laterally extending tubes and connected to said lower drum, a row of tubes connecting said end wall header to said upper drum, and means forming a direct structural connection between said side and end wall headers.

18. A steam boiler having an upper steam and lwater drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, a partition defining the inner side wall of a furnace chamber laterally adjoining the space containing said tube bank and communicating therewith at its rear end only, means defining the remaining walls of said furnace chamber and tube space, a row of tubes connected to said upper drum and laterally spaced from said tube bank and extending along the outer side wall of said furnace chamber, a horizontal header connected to the lower ends of said side wall tubes, a row of tubes extending laterally'from said lower drum and connecting said lower drum to said side wall header, means at lthe front end of said furnace chamber for burning fuel in suspension therein and effecting a substantially horizontal ilow of heating gases rearwardly through said furnace chamber and thence through said tube space, a horizontally extending header along the rear wall of said furnace chamber and connected to said lower water drum, and a row of spaced tubes connecting said rear wall header to said upper drum and arranged to cool the rear wall of said furnace chamber.

19. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, means defining a furnace chamber laterally adjoining the space containing said tube bank and including a row of spaced tubes extending laterally from and connected to said lower drum, means closing the spaces between said laterally extending tubes and dening the floor of said furnace chamber, means at the front end of said furnace chamber for burning fuel in suspension therein, and an ash receiving opening extending transversely of said furnace chamber at the rear end thereof.

20. A steam boiler having an upper steam and water drum, a lower water drum, a bank of steam generating tubes extending between and connected to said drums along the length thereof,

'means forming a furnace chamber laterally adjoining the space containing said tube bank 4and communicating therewith at its rear end, means at the front end of said furnace chamber for burning fuel in said furnace chamber and eifecting a substantially horizontal iiow of heating gases rearwardly through said furnace chamber and thence through said tube space, baille means extending transversely of said tube space and arranged to divide said tube space into a plurality of serially connected gas passes extending transversely of said tube bank, steam superheating tubes positioned in the gas pass opening to said furnace chamber and at the outer side of said tube bank, and means for supporting,s'aid superheating tubes from said tube bank.

21. A steam boiler comprising an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, a partition forming the inner side of a furnace chamber and separating the same from a laterally adjoining space containing said tube bank, means dening the remaining sides of said furnace chamber and tube space, said furnace chamber and tube space communicating at their rear ends only, means at the front end of said furnace chamber for burning fuel and effecting a substantially horizontalilow of heating gases rearwardly through said furnace chamber and thence through said tube space, and the tubes in the tube rows at the rear end of said bank nearest said furnace chamber being spaced apart a greater distance than the tubes in the remaining rows of said bank to form a slag screen between the tubes in the remaining rows and said furnace chamber.

22. A steam boiler comprising an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, a partition forming the inner side of a furnace chamber and separating the same from a laterally adjoining space containing said tube bank, means defining the remaining sides of said furnace chamber and tube space, said furnace chamber and tube space communicating at their rear ends only, means at the front end of said furnace chamber for burning fuel and eifecting a substantially horizontal iiow of heating gases rearwardly through said furnace chamber and thence through said tube space, the tubes in the tube rows at the rear end of said bank nearest said furnace chamber being spaced apart a greater distance than the tubes in theremaining rows of said bank' to form a slag screen between the tubes in the remaining rows and said furnace chamber, and a steam superheater positioned in. said tube space at the opposite side of said tube bank from said furnace chamber.

23. A steam boiler having an upper steam and water drum, a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof and disposed at both sides of the plane including the longitudinal l for burning fuel and effecting a substantially horizontal flow of heating gases longitudinally through said furnace chamber and "thence,

through said tube space, and a steam superheater positioned in said tube space on the side of said axial plane opposite said furnace chamber.

24. A steam boiler comprising an upper steam and water drum. a lower water drum, a vertically disposed convection heated bank of steam generating tubes extending between and connected to said drums along the length thereof, a partition forming the inner side of a furnace chamber and separating the same froma laterally adjoining space containing said tube bank, means defining the remaining sides of' said furnace chamber and tube space, said furnace chamber and tube space communicating at their rear ends only, a row of tubes connected to said drums and laterally spaced from said partition and extending along the outer side of said furnace chamber, means at the front end of said furnace chamber for burning fuel and effecting a substantially horizontal flow ,-of heating gases rearwardly through said 4furnace chamber and thence through said tube space, and vertical baille means extending from said upper drum to said lower drum and arranged transversely of said tube bank to divide said tube space,into a plurality of serially connected gas passes having a substantially horizontal flow of heating gases therein in thermal contact with said tube bank.

25. In a uid heater, a furnace boundary structure adapted to be exposed in operation to high temperatures and comprising a row of spaced fiuid heating tubes, a series of metallic projections mounted on said tubes and arranged to project into the intertube spaces, refractory material between said projections in contact with said tubes and arranged to close the intertubespaces, and means for connecting projections on'adjacent tubes.

26. In a fluid heater,l a separating `wall4having opposite sides adapted to be exposed in operation to high temperatures and comprising a row of vertically disposed spaced fluid heating tubes, a series of metallic projections mounted on said tubes and arranged to project into the intertube spaces, refractory material between said projections in contact with said tubes and arranged to close the intertube spaces, and means for 1ntegrally connecting projections on adjacent tubes.

27. In a uid heater, a row of spaced fluid heating tubes having a series of metallic projections mounted on and spaced along opposite sides of said tubes, and arranged to project into the inter-tube spaces, andconnecting means between projections on adjacent tubes to tie said tubes together along their length.

28. A steam boiler having a pair of'horizontally disposed upper and lower drums, a bank of vertically disposed water tubes 'extending between and connected to saiddrums along the length thereof, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at one end thereof, said means including a vertically disposed partition extending along one side of said heating lan'e and having tubes' provided with refractory-supporting'- metallic projections at the heating lane side thereof arranged to form a vertically extending recess, a vertically disposed baille extending.'

transversely of said heating lane and fitting into the recess in 'said partition, and means for burning fuel in said combustion lane and arranged to permit a serial fiow of heating gases through said combustion and heating lanes.

29. A steam boiler having a pair of horizontally disposed upper and lower drums, a bank of ver- 1 tically disposed water tubes extending between and connected to said drums along the length thereof, means forming a longitudinally extend` y ing combustion lane and a heating lane laterally adjoining said combustion lane and containing saidtube bank and communicating with said combustion lane at one end thereof, said means including a row of tubes with refractory material therebetween and forming a vertically disposed longitudinally vextending partition separating and forming one side of said combustion and heating lanes, means for burning fuel in said combustion lane and arranged to permit a serial flow of heating gases through said combustion and heating lanes, and said partition and partition-forming tubes being spaced a substantial distance from the laterally adjacent tubes of said tube bank to provide a heating gas distribution space between said partition and tube bank.

ERVIN G. BAILEY. PERRY R. CASSIDY. RALPH M. HARDGROVE. DAVID S. JACOBUS.

CERTIFICATE or CORRECTION.

mem No. 1,999, 984. Ami 3o. |935.

ERVIN G. BAILEY, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column,

' line 52,- for "simultaneously" read simultaneous; pageS. first column, line l0, claim 3, for "baffle wall" reud'parttion; and that the said Letters Patent should be read with these corrections therein that the same. may conform to vthe record of the case in the Patent Office.

* Signed and sealed this 16th day of July, A. D. 1935.

Leslie Frazer (Seal) Q Acting Commissioner of Patents. i